1. Field of the Invention
The present invention relates to a multivision device, and more particularly to a multivision device configured by stacking a plurality of projection units, which accommodate rear projection projectors, both horizontally and vertically, and that displays one large screen picture by enlarged projection of pictures projected from this multiplicity of projection units.
2. Description of the Related Art
As the size of screens in display units has increased in recent years, attention has been given to projectors that enlarge and project pictures on the screen.
An example of this type of projector is the liquid crystal projector that displays pictures based on video signals entered into a liquid crystal panel, enlarges these pictures, and projects them for display onto a screen. The liquid crystal projector is the most common type of display device because the display device is thin and light, it is driven by a low voltage, and has a low power consumption.
Recently, with the desire for larger screens, so-called multivision devices, which enable the display of large screen pictures by combining a plurality of the above projectors, have been put into use in corporate advertising and displays for various events.
Generally, a multivision device is configured either as a device comprising a plurality of projectors accommodated inside a cabinet and one screen, or as one projection unit comprising a projector and screen set. The so-called CUBE device is configured as a single projection device in which nine projection units are stacked in a three horizontal by three vertical (3xc3x973) configuration.
In such multivision devices, the large screen display makes higher picture precision an issue requiring urgent attention and various proposals have been put forward regarding this.
To achieve highly precise pictures using multivision devices, it is important that the borders between adjoining pictures are as unobvious as possible. Proposals such as Japanese Patent Laid-open No. H6-178327, U.S. Pat. No. 5,956,000, and Japanese Patent Laid-open No. H9-326981 have been put forward to achieve this objective.
In the multivision devices of these proposals, parts of the pictures projected from adjoining projection units overlap each other and a single large picture is created by smoothing the image data in these overlapping sections. This method attempts to make borders between adjoining pictures less obvious.
Other proposals are shown in Japanese Patent Laid-open No. H8-82854 and Japanese Patent Laid-open No. H8-152677. In these proposals, screens are not provided for each of a plurality of projection units but rather, a plurality of screens is combined to create a large-scale screen unit. One large picture is created by placing this multiplicity of screens in front of horizontally and vertically stacked projection units. This attempts to make the borders between adjoining pictures less obvious.
Another proposal is described in Japanese Patent Laid-open No. H9-211386. In this proposal, light-adjusting material is placed between the projector and the screen in an attempt to reduce the amount of light in the overlapping sections. The result is that the borders between adjoining pictures are made less obvious.
Methods to obtain highly precise pictures by configuring a picture projection system using a multivision device have also been proposed. For example, there is the picture projection system proposed by this applicant and disclosed in Japanese Patent Laid-open No. H9-326981.
The picture projection system of this proposal comprises: a device for generating highly precise image data; an image projection device that has a plurality of projectors for projecting at least part of this highly precise image data; and an image processor that selects and processes at least part of this highly precise image data and sends it to the above multiplicity of projectors.
Such a picture projection system provides a projection method where the above image projection device is used to overlap parts of the pictures from each projector and create one large picture. In addition, the system uses the above image processor to process pictures so that the overlapping sections are joined smoothly. To enable this image processing to occur, the pictures projected onto the screen by each projector are photographed by a photographic device such as a digital camera and parameters, such as the position, colour, and brightness of each picture, are acquired. An image processor in a personal computer is then used to reference these parameters, process them into the original pictures and send them to each projector. In this way, by photographing the plurality of pictures as if they were one picture, smooth links between pictures are achieved and the precision of pictures is improved.
Proposals for technology to improve the precision of pictures are described, for example, in Japanese Patent Laid-open No. H6-284363 and U.S. Pat. No. 5,902,030. In these proposals, the optical axis of each projector has an offset so that it is not at a right angle to the screen. Projectors, each with a different offset direction, are arranged so that their projecting parts arranged above and below each other. By thus making it appear that they irradiate from one light source, the effects of differences in directivity around the borders of adjoining images, that is the unevenness in lighting, is mitigated.
Other technology is described in, for example, Japanese Patent Laid-open No. H5-316454, Japanese Patent Laid-open No. H8-154222, and Japanese Patent Laid-open No. H7-333727. In the proposal described in Japanese Patent Laid-open No. H5-316454, by providing a mechanism that can vary the position of projection units in a vertical direction within the housing in which they are accommodated, the main beams of light from the stacked projection units are all headed towards the viewer. This suppresses changes in the luminance of each screen.
In a proposal described in Japanese Patent Laid-open No. H8-154222, the housing that accommodates the projection units includes a mechanism for enabling variation in the vertical position of the projection units and a mechanism for enabling variation in the distance between the housing and the screen. When the size of the screen that will be combined with the projection units is selected, the vertical position of the projection units and the distance to the screen will be changed using these mechanisms in accordance with the selection. This enables fine adjustment of the screen size.
Furthermore, in the proposal described in Japanese Patent Laid-open No. H7-333727, the projection units can slide freely backwards and forwards within the housing in which they are accommodated. This means that during maintenance, the projection units can be easily removed, without removing anything else, and worked upon.
In Japanese Patent Laid-open No. H6-178327, U.S. Pat. No. 5,956,000, Japanese Patent Laid-open No. H9-326981, Japanese Patent Laid-open No. H8-82854, and Japanese Patent Laid-open No. H8-152677, technology is proposed for forming large, borderless pictures by overlapping parts of images projected from adjoining projection units.
However, in display units for displaying one large picture on a screen by stacking small projection units that are easily transportable, such as the CUBE multivision device, and enlarging the projection from each of these, it is difficult to create large, borderless pictures. Also, while there have been proposals to enable the creation of large pictures without joints by designing screens for multivision devices, these proposals required highly precise positioning because there are boundary sections between adjoining pictures. Also, any slight movement of the screen or projected light will cause the douser, which prevents adjoining projected light, to form a shadow so that a highly precise picture will not be attainable.
In, for example, the Japanese Patent Laid-open No. H9-211386 described above, there is a proposal relating to a location for light adjusting material. However, the problem here is that this cannot be applied when, for example, a CUBE multivision device configured from a combination of a plurality of projection units is used.
In the image projection system as disclosed in Japanese Patent Laid-open No. H9-326981 as described above, configuration of an image projection system using a multivision device enables more highly precise pictures to be obtained. However, this type of image projection system, as explained above, involves the combination of a plurality of units in a CUBE multivision device. Therefore, the light of the picture projected from a projector next to a projector attempting to take photographs for calibration makes it difficult to photograph the image patterns to be photographed normally. That is, the effect of the adjoining pictures means that the compensation function of this image projection system cannot be used effectively.
Next, Japanese Patent Laid-open No. H6-284363 and U.S. Pat. No. 5,902,030 provide proposals that cater for instances when projection units are combined in two horizontal and two vertical rows. However, the proposal does not cater for combinations of larger quantities. That is, these proposals do not cater for multivision devices. In the methods described in these patents, that is Japanese Patent Laid-open No. H6-284363 and U.S. Pat. No. 5,902,030, projectors with different offset directions are used. Therefore, all projection units used cannot be the same and thus the resultant device will be very expensive.
Furthermore, in the technology described in, for example, Japanese Patent Laid-open No. H5-316454, Japanese Patent Laid-open No. H8-154222, and Japanese Patent Laid-open No. H7-333727, a configuration with a mechanism that moves forwards and backwards within the projection units, a mechanism that moves up and down in a perpendicular direction, and a mechanism for slight angle changes is proposed. However, there is no reference to angle changes in a horizontal direction.
With the foregoing problems in mind, it is an object of the present invention to enable highly precise pictures with no visible borders between adjoining pictures by configuring a system so that adjoining pictures overlap on the screen to form one large screen picture.
A further object of the present invention is to provide a multivision device that can simply adjust the position of light adjusting material.
A still further object of the present invention is to provide a multivision device in which the effect of adjoining pictures is removed thereby allowing accurate calibration by an image projection system even when calibration photography is done using an image projection system.
An even still further object of the present invention is to provide a multivision device in which quality pictures are obtained as if projected from one light source by using a plurality of the same projection units and changing the direction of projections from the projectors inside the plurality of projection units in accordance with their position in a horizontally and vertically configured stack.
The multivision device of the present invention comprises: a projection device constituted by an array of a plurality of projection units each of which comprises a rear projection projectors and housing that supports this rear projection projector; and a screen, which is placed in isolation from the projection device and displays pictures projected from the projection device, and in this multivision device, pictures projected from adjoining projection units overlap on the screen to form one picture on the screen.